Digit wheel assembly



DIGIT WHEEL ASSEMBLY 4 /ff/f p ,ZM

l /7 /54/ "2 (44" P77 Z INVENTOR Mzz/mf i? Enea@ ue United' States Patent O U.S. Cl. 101-110 7 Claims ABSTRACT OF THE DISCLOSURE A digit wheel assembly is disclosed for use with imprinters, the assembly consisting of (1) a digit wheel unit including a plurality of digit Wheels mounted on a common digit wheel shaft; (2) a carrier unit for the digit wheel unit, the carrier unit being slotted at both ends thereof to respectively receive the ends of the digit wheel shaft and the carrier unit being downwardly biased by a compression spring with respect to the underside of the print bed portion of the base of the imprinter; (3) a pair of U-shaped brackets xedly secured to the underside of the base, each of the brackets including vertically disposed guide paths for the respective ends of the digit wheel unit carrier; (4) a pair of adjustment screws respectively threaded through the U-shaped brackets t vertically move the carrier unit upwardly against the compression springs to there-by establish an optimum initial vertical position of the digit wheel unit; (5) a plurality of L-shaped pawls, the vertical legs of which respectively engage gear faces respectively connected to the digit wheels and the horizontal legs of which are downwardly biased by a plurality of detent compression springs mounted in the base of the carrier unit; (6) a pawl shaft which passes through the vertex of all of the pawls, the pawls being attached for rotational movement around the shaft by the action of the detent compression springs to thereby engage the respective gear faces; (7) a pair of eccentric bearings rotatably mounted in said carrier unit, the pawl shaft being eccentrically mounted at both ends thereof in eccentric bearings; and (8) means for rotating the eccentric bearings to transfer vertical movement to the pawl shaft and the pawls connected thereto and thus rotational movement to the digit wheels whereby an optimum, initial rotational position of the digit wheel unit is elfectuated.

BACKGROUND OF THE INVENTION This invention relates to digit wheel assemblies and in particular to means for establishing optimum, initial, vertical and angular positions of such assemblies with respect to the print bed portion of an imprinter base. Referring to the U.S. Pat 3,279,369 granted to William A. Wight on Oct. 18, 1966 and assigned to the assignee of the present invention, there is illustrated therein an imprinting device which prints both the lixed and variable data relating to a business transaction such as a sale-of merchandise. The xed data source shown in this patent typically is a credit card or plate 46 which is carried on a customers person and produced at the time of sale. This card usually contains at least the customers name and account number which is used by automatic data processing machinery to identify the customers account. The variable data of the transaction is produced by digit wheels indicated at 114 in the patent and includes at least the amount of the transaction, this amount also being utilized by the data processing machinery to maintain the customers account.

Typically, the invoices produced by the imprinting device disclosed in the above patent are directly read by optical character reading equipment, the output signals 3,521,556 Patented July 21, 1970 from the reading equipment being applied to card punching equipment or directly to the data processing equipment. The document throughput rate (that is, the number of documents read in a given time interval) of the optical character reading equipment is effected by the quality 0f the print produced by the imprinting device. Thus, it is desirable that no smudges appear and that the stroke width of the printed characters be substantially uniform. To minimize smudging, it is necessary that the printing pressure generated during the imprinting operation be optimum and this to a large extent means that the spacing between the roller platen of the imprinter and the upper face of the digits on the credit card and the digit wheels be optimum. Thus, it is desirable that the initial, vertical position of the digit wheel unit be appropriately adjusted. Further, to insure constant stroke widths of the printed digits or characters, it is desirable that the upper face of the digit characters be substantially parallel with respect to the plane of the roller platen. Hence, the initial angular or rotational position of the digit wheel unit should also be appropriately adjusted.

A further factor of importance is the amount of time required to effectuate the above adjustmentsthat is, the optimum, initial, vertical and angular positions of the digit wheel unit. If too much time is required in making these adjustments, it follows that the manufacturing cost of producing the imprinting devices may well get out of hand.

SUMMARY OF THE INVENTION It is the primary object of this invention to provide an improved digit wheel assembly for use with imprinting devices wherein optimum initial, Vertical and/or angular positions of the assembly may be efectuated.

It is a further object of this invention to provide an improved assembly of the above type wherein the above adjustments can be quickly made.

Other objects and advantages of this invention will become apparent upon reading the appended claims in conjunction with the following detailed description and the attached drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of an illustrative embodiment of a digit wheel assembly in accordance with the invention.

FIG. 2 is an end view of the assembly of FIG. 1 together with a rack member used in conjunction therewith.

FIG. 3 is a partial cross-section of the embodiment of FIG. 1 taken along line 3 3.

FIG. 4 is a cross-sectional View taken along the line 4 4 of FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring to FIGS. l through 3, the digit wheel assembly is shown to be divided into four basic components; namely a digit wheel unit carrier 10, (2) a digit wheel unit 12, (3) a detent pawl unit generally indicated at 14, (4) a carrier support 16. Generally speaking, as will be seen more clearly hereinafter, the carrier support 16 is fixedly secured by appropriate means to the underside of the print bed portion of the base plate 18 (see FIG. 3) of the imprinter. The digit Wheel carrier unit 10 is resiliently mounted with respect to base plate 18 via compression springs 20 and 22, see FIG. 3. Further, the digit wheel unit carrier 10 carries the digit wheel unit which consists of a digit wheel shaft 24 upon which are mounted digit wheels 26-36 and appropriate spaces. The detent pawl unit 14 comprises a pulrality of pawls respectively corresponding with the digit wheels, the purpose of the pawls being to aid in the leveling of the faces of the characters or digits disposed around the periphery of each of the digit Wheels so that the faces are parallel with the print roll during an imprinting operation to thereby produce an impression having uniform stroke width. Having described in general the operation and the relation of the various basic components of the digit wheel assembly, each of the component parts Will now be described in more detail.

DIGIT WHEEL UNIT CARRIER As can be seen in FIG. 3, the digit wheel unit carrier 10 is substantially U-shaped, the carrier comprising a horizontal leg 38, vertical legs 40 and 42, and horizontal flanged portions 44 and 46 disposed generally at the top of the vertical legs 40 and 42, respectively.

Referring to FIG. l, it can be seen that the horizontal flanged portions 44 and 46 include slotted portions disposed in the top thereof, these slotted portions being indicated respectively at 48 an 50. These slotted portions receive the shaft 24 of the digit wheel unit and control the horizontal and vertical position of the shaft. The slots 48 and 50 respectively include spring wells 52 and 54 in which are mounted compression springs and 22. The springs 20 and 22 respectively include looped ends, the looped end for spring 20 being indicated at 60 in FIG. 3. The looped ends are placed on each end of the shaft, as indicated in FIG. 3, and in grooves disposed at the bottom of the slots 48 and 50, one of the slots being indicated at 62 in FIG. 3.

Also disposed in the horizontal flanged portions 44 and 46 are a respective pair of inverted wells 64 and V66 in the top of which are disposed bearing plates 68 and 70. As will be brought out in more detail hereinafter, mounted within wells 64 and 66 and against the plates 68 and 70 are two respective adjustment screws one of which is indicated in well `66 at 72, the purpose of the adjustment screws being to vertically position the digit wheel unit carrier together with the digit wheel unit and thereby establish an initial vertical position of the digit wheels 26 through 36 where the printed characters produced thereby are optimized for optical character reading.

Referring to the upper side of lower horizontal leg 38 of the digit wheel unit carrier 10, there are shown, in FIG. 3, a plurality of teeth which form slots 7484. Through these slots are disposed a plurality of racks (for example, see rack 85 of FIG. 2) which engage gear faces (86-96) respectively connected to the digit wheels 26 through 36. As is clear from the before mentioned patent, horizontal movement of the racks produces corresponding rotational movement in the associated digit Wheels. In FIG. 4 a rack 98 is indicated in phantom lines and is shown in engagement with the teeth of gear face 94. Thus, the slots 74 through 82 are shown in FIG. 3 form passageways for the racks, the racks not being shown in FIG. 3.

On the underside of the lower horizontal leg 38 of the digit Wheel unit carrier 10 is disposed a further plurality of teeth which form slots for respectively receiving the lower legs of pawls (described in more detail hereinafter) which are respectively associated with the digit wheels. Only the slots 100-104 for the pawls are shown in FIG. 3, it being understood that a slot is formed on the Iunderside of the horizontal leg 38 for each digit wheel location along the digit wheel shaft 24. As seen in FIG. 3, within each of the slots 160-104 are disposed respective spring wells 106-108 and mounted within the spring wells are respective compression springs 110-114, these springs effectuating the detenting action of their associated pawls, as will be described in more detail hereinafter.

DIGIT WHEEL UNIT 12 The digit wheel unit has already been substantially described hereinbefore. Basically, this unit includes shaft 24 upon which is mounted digit wheels 26-36 and their respective associated gear faces 86-96. On each of the digit wheels are disposed a plurality of characters or digits which effectuate printing of variable information on documents such as sales invoices placed upon the base 18, see FIG. 3. As is Well-known in the art, various types of spacers are placed between the digit wheels to maintain accurate character pitch. Further, other spacers (not shown) are employed (l) Whenever a digit does not occur at a location where normally it would appear for a given character pitch and (2) to provide clearance of the digit wheels from the carrier 10, see rectangular spacer 97 in FIGS. 1-3.

DETENT PAWL UNIT 14 In FIG. l there is shown a top View of the pawls 116- 126, an end view of the pawl 126 being shown in FIG. 2. Referring to FIG. 4, there is shown a cross-sectional view of pawl 124 illustrating its relation to gear face 94 and detent spring 128, this spring serving the same purpose as springs -114 of FIG. 3. yEach of the pawls 116- 126 is the same and thus a description of pawl 124- of FIG. 4 will suffice for the other pawls. Pawl 124 is L- shaped with the long, vertical leg thereof having a triangular member attached thereto which is adapted for engagement with the gear face 94. The pawl is `rotatably mounted at the vertex thereof on shaft 132, the mounting of shaft 132 being described in more detail hereinafter with respect to FIG. 3. The short, horizontal leg 134 projects into slot 136, this slot being formed by the teeth disposed at the bottom of the horizontal leg 38 at carrier 10 and corresponding to the slots 100 through 104. The compression spring 128 moves the pawl leg 134 downwardly thereby biasing the leg 130 so that the triangular member 131 tends to engage and maintain in a fixed position the gear face 94 and its associated digit wheel 34. However, any external force applied via rack 98 readily overcomes the detenting action of the pawl 124, and thus setting of the digit wheels is easily eifectuated. The compression spring 128 is captured between the carrier 10 and the leg 134 as long as the pawl 124 engages gear face 94 as shown in FIG. 4. On the vertical leg 130 of the pawl is included a leaf or dellecting spring finger 138 that allows a centering and locking block (not shown) to uniformly set all of the pawls. Thus, during an imprinting operation, the block is moved into engagement with the spring fingers of the pawls thereby effectuating a tight engagement between the gear faces and the pawls to cause absolute centering of the selected digits in the print bed and to prevent any rotational movement of the digit wheels during an imprint operation and thereby eliminate any tendency for the printed characters to smudge.

Referring to FIG. 3, there is shown the pawl shaft 132, upon which the pawls are mounted. The shaft is eccentrically titted into two eccentric bearings 140 and 142. As can be seen in FIG. 2 the shaft 132 is displaced from the center of the bearing 142 to thereby facilitate the initial angular adjustment of the digit wheels as will be shown in more detail hereinafter. The bearings 140 and 142 are respectively rotatably mounted in a pair of horizontally extending legs 144 and 146 which are integrally connected to the junction of the vertical legs 40 and 42 and the lower horizontal leg 38 of the carrier 10. Integrally connected to the bearings 140 and 142 are hexagonal nutheads 148 and 150 to facilitate the rotation of the bearings 140 and 142. Dog set screws one of which is shown at 154 (FIG. 2) are threaded through appropriate holes in the bottom of legs 144 and 146 respectively to lock the eccentric bearings 140 yand 142 in place after the desired initial, angular position of the digit wheels has been obtained, this being brought out in more detail hereinafter.

CARRIER SUPPORT UNIT 16 As can best be seen in FIG. 2, the support unit 16 comprises a pair (see FIG. 1) of substantially U-shaped units, the unit of FIG. 2 consisting of a pair of vertical legs 156 and 158, a lower horizontal leg 160 and two horizontal tlanged portions 162 and 1'64. The horizontal flanged portions 162 and 164 arev xedly secured to the underside of the print bed portion of the imprinter base 18, by appropriate means 166 and'168 as indicated in FIG. 2. The horizontal lianged portions 44 and 46 of the digit wheel unit carrier are slidably mounted within vertically disposed guide means in the U-shaped support unit 16 as can best be seen in FIG. 2. The adjustment screw 72 is threaded through the horizontal leg 160 and into the well 66 of the carrier 10, the vertical leg 46 thereof being partially broken away as shown in the drawing. Screw 72 includes an hexangonal shaped hole (not shown) in the lower end thereof which receives an Allen wrench to thereby effectuate the desired vertical position. Nut 170 mounted on screw 72 locks the screw in place once the desired vertical position of the screw 72 is attained. As stated hereinbefore, the vertical adjustment of screw 72 causes the digit wheel unit carrier of unit 10 to move against compression spring 22, which in turn, is fitted against the underside of base plate 18. Thus, since the digit wheel unit 12 rides in the carrier 10, the unit 12 can be vertically positioned so as to optimize the printing pressure generated during imprint operation.

OPERATION As stated hereinbefore, the basic purpose of this invention is to effectuate optimum initial vertical and angular positions of a digit wheel assembly for use with imprinting devices. The optimum vertical position is obtained by threading adjustment screw 72 through support 16 and against bearing plate 70 until a predetermined vertical position is arrived at, there being a corresponding adjustment of the adjustment screw (not shown) which is disposed in the well 64 of the horizontal flange 44 of the carrier 10. Once this predetermined position is arrived at, the operator next adjusts the angular position of the digit wheel -assembly by rotating the eccentric bearings 140 and 143 simultaneously with a special U- shaped wrench (not shown) which engages the hexagonal nuts 148 and 150 simultaneously. Rotation of the bearings either clockwise or counterclockwise will move the pawl shaft 132 in a substant-ally vertical direction either upwardly or downwardly because of the eccentric mounting of this shaft within the bearings. The vertical movement of the pawls is translated via the triangular members (such as triangular member 131 of FIG. 4) into a rotational movement of the gear faces and digit wheels, all of the digit wheels being rotated simultaneously. The optimum amount of rotational movement is that amount which will level the face of the digits disposed on the wheels with respect to roller platen so as to provide -a uniform stroke width impression.

Once the Vertical and angular positions of the digit wheels are established as above, a sample imprint is taken and if the imprint is not optimum one or both of the above discussed adjustments are repeated until the print produced by the digit wheel assembly is optimum. When optimum settings are obtained both as to the vertical and angular position of the digit wheels, the nut 170 (see FIG. 2) is locked into place to maintain the initial vertical position and the screws, one of which is shown at 154, are also locked to x the initial angular position.

From the foregoing, it can be seen that the objects and advantages claimed for the invention are etfectuated by the preferred embodiment described herein. In particular, it can now be seen how the initial vertical and angular position of a digit wheel assembly can be readily and quickly optimized by the foregoing embodiment of the invention.

Numerous modifications of the invention will become apparent to one of ordinary skill in the art upon reading the foregoing disclosure. During such a reading it will be evident that this invention provides a unique digit wheel assembly for accomplishing the objects and advantages herein stated. Still other objects and advantages and even further modifications will become apparent from this disclosure. It is to be understood, however, that the foregoing disclosure is to be considered exemplary and not limitative, the scope of the invention being defined by the following claims.

What is claimed is:

1. A digit wheel assembly for use with an imprinting device having a travelling roller platen and a base with a print bed portion comprising:

a support unit fixedly secured to the print bed portion of the base of the imprinting device;

a plurality of wheels having digits or characters disposed around the periphery thereof for electuating printing of information on documents disposed on the imprinting device base during an imprinting operation;

a shaft upon which all of said digit wheels are mounted,

said shaft being mounted with respect to said support unit;

a plurality of pawls respectively associated with said plurality of digit wheels and respectively engaging a plurality of gear faces respectively connected to said plurality of digit wheels;

a pawl shaft upon which all of said plurality pawls are rotatably mounted in relatively fixed positions along said pawl shaft;

means for adjusting the vertical position of said pawl shaft whereby said digit wheels are rotated in accordance with the vertical movement of the pawls whereby the initial angular position of said digit wheels with respect to said print bed portion of the imprinter base may be adjusted; and

means for locking said adjustment means whenever the optimum angular position with respect to said print bed portion is obtained to thereby render the stroke zvidths of the printed information substantially uniorm.

.2.. A digit wheel assembly as in claim 1 further compr1smg:

a support unit xedly secured to the print bed portion of the base of the imprinting device, said support unit including vertically disposed guide means;

a plurality of wheels having digits disposed around the periphery thereof for etfectuating printing of said variable data on documents disposed on said print bed portion;

a digit wheel shaft upon which all of said digit wheels are mounted;

a carrier unit including means at both ends thereof for supporting said shaft, said carrier unit being slideably disposed within said vertically disposed guide means of said support means; l

spring means disposed between said base and the carrier unit biasing said carrier unit away from said base;

adjustment means movably connected with respect to said support means for vertically moving said carrier unit through said vertically disposed guide means to thereby adjust the initial vertical position of the digit wheels with respect to the print bed portion of said imprinter base;

means for locking said adjustment means whenever the optimum vertical position of the digit wheels with respect to said print bed is obtained to thereby minimize any smudging which may occur upon operation of the imprinting device.

3. An assembly as in claim 2 where said support means for the carrier unit includes a pair of said vertically disposed guide means which are respectively disposed at the 7 opposite ends of said carrier unit, said carrier unit being slideably disposed in both of said guide means.

4. An assembly as in claim 3 where each said support means is substantially U-shaped, the said ends of the carrier unit being respectively, slideably disposed between the vertical legs of the U-shaped support means.

5. An assembly as in claim 4 Where said vertical position adjustment means includes a pair of screws respectively threaded through the lower horizontal legs of said U-shaped support means, the upper ends of the adjustment screws respectively engaging the undersides of said ends of the carrier unit.

6. An assembly as in claim 1 where said means for vertically moving the pawl shaft includes a pair of eccentric bearings respectively disposed at both ends of the pawl shaft, the bearings being rotatably mounted at both said ends of the carrier unit and the pawl shaft being ixedly secured at both ends thereof into the eccentric bearings.

7. An assembly as in claim 6 where said carrier unit is substantially U-shaped, the underside of the horizontal leg thereof containing a plurality of slots respectively corresponding to said plurality of pawls, each of said pawls being substantially L-shaped, the lower legs of pawls being respectively disposed in said plurality of slots, a plurality of detent compression springs respectively disposed in said slots, said pawls being mounted at the vertices thereof on said pawl shaft so that the action of said compression springs on the respective lower legs of the pawls tends to force all pawls into engagement with their respective gear faces.

References Cited UNITED STATES PATENTS 931,170 8/1909 Wilhelm l0 l-99 1,906,304 5/1933 Barrett lOl- 93 2,909,998 10/1959 Maul 'lOl-269 2,994,265 8/1961 Hurlbut et al. 101-269 3,116,687 1/1964 Harding lOl-269 3,138,091 6/1964 Maul 101-45 3,385,213 5/1968 Stephan 101-110 3,405,634 10/1968 Maul et al 101-285 X WILLIAM B. PENN, Primary Examiner U.S. C1.-X.R.

lOl-45, 99, 269 

